The invention relates to a method, an apparatus, and software for guiding users during optical inspection and measurement of coated and noncoated substrates.
In the semiconductor industry, a plurality of processing steps are required for producing integrated circuits. In this process, structures are applied on substrates, especially on silicon wafers, by means of diverse chemical and physical processes. In so doing, dust particles or defects on the substrate or on the structures are fatal to the success of the subsequent processing steps or for the subsequent functioning of the integrated circuit. The same also applies to inaccurate thicknesses or inaccurate optical parameters on the layers applied on the substrate and by means of which the structures are produced. Therefore, devices for detecting dust particles and defects and for measuring the layer thickness are mandatory for producing semiconductors. To this end, optical systems are especially appropriate for inspection, defect detection and layer analysis, since they work in a contactless and destruction free manner.
There exist a number of different optical inspection, defect and layer analysis systems in the state of the art and their use has been successful in the analysis of structured and non-structured wafers.
Such optical systems are used in particular in the production line of semiconductor manufacturers. They are fully automated. Pull-out arms remove a wafer from a wafer cassette and transport it under a microscope in order to inspect the wafer surface at the appropriate magnitude. The dust particles and defects are recognized visually or with a video or CCD camera and then analyzed. The layers applied on the wafer are measured on a very small measurement spot; and their visual material properties and thicknesses are found. With the aid of an automatically moveable table many points on the wafer can be inspected and measured. The user specifies the appropriate inspection and measurement programs.
In layer analysis systems, the visual material properties (primarily the refraction index n, absorption coefficient k, and the reflectivity) of the substrates and the layers, applied thereon, their thicknesses and layering are determined. These usually very thin layers are made of different substances, such as silicon dioxide, silicon nitride, aluminum or paint; and their thickness ranges from approx. 1 nm to more than 50 xcexcm. The optical measurement is done with spectrophotometers and/or ellipsometers or spectroellipsometers. The measurement spot to be examined on the wafer is illuminated with light of different wavelengths, which can range from ultraviolet to infrared. The reflected light is measured and analyzed.
Since the goal in manufacturing wafers is to produce ever thinner layers and finer structures, the requirements on the accuracy of the optical measurement systems, with which the dimensional accuracy of the layers and structures can be proven, increases proportionally. In addition to the demand for increased accuracy, one must also consider the endeavor to increase the number of items produced. Thus, for example it is necessary in the continuous production of wafers to inspect and measure them at ever shorter time intervals and, if possible, online. In so doing, it is important that the optical measurement systems be user friendly and easy to operate.
The principle operating sequence consists of entering information in order to set up a measurement recipe (run parameters, run programs, measurement parameters), to perform the measurements and display the measurement results. The run programs determine, for example, the wafer handling, thus which wafer is taken from which cassette and at which coordinate points the wafer is supposed to be examined. The alignment of the wafer, in which the wafer is aligned with respect to the coordinate system of the optical measurement system, the depositing of the wafer on a motorized table and the moving of the wafer under the microscope are usually fully automatic.
Past optical inspection and measurement systems show, for example, one or more window(s) on a computer screen, where the run and measurement parameters to be set or the run and measurement programs are listed as key words. On the left hand edge of the list of key words there is a symbol, shown as an arrow, which moves in the vertical direction by means of the cursor keys of the computer keyboard and thus can be moved past the key words. If in this manner the arrow is positioned on a key word that indicates a parameter value, the parameter value can be entered. If the key word means a run or measurement program, it is executed by depressing the return key. To retrieve the preceding window or another window, the arrow is moved to the corresponding position and the return key is depressed. In addition, the function keys of the computer keyboard can be used for help functions. These known menu guidance procedures for entering measurement parameters and executing and displaying the results of measurement programs are time consuming and not very easy to survey.
The object of the invention is to provide a user guide for optical inspection and defect detection on the surfaces of substrates and/or layers applied thereon, and for optical measurement of substrates and layers, applied on the substrates, with a layer analysis system that is simple, easy to survey, and fast and easy to learn.
This problem is solved according to the invention with an integrated recipe and data browser. Other embodiments are apparent from the features described herein. In addition, interactive research measurements can also be executed during a recipe setup. In this respect, the set values found during optimal measurement can be incorporated into the current recipe.
The integrated recipe and data browser serves to set up the device settings and simultaneously display the data. The word xe2x80x9cintegratedxe2x80x9d is used herein to express the simultaneousness of the display of the recipe and the data browser on the screen and the access to both browsers. The recipe and data browser can be divided in any way on the screen. Preferably, the data browser is arranged in a screen area below the recipe browser. This arrangement of the browser is the same for all basic operations, namely setting up measurement recipes, performing measurements, viewing results and also finding again measurements that have already been performed or earlier measurements. Thus, it is easy to learn, easy to handle and very comfortable for the user.
The user sets up the recipe, which is defined, among other things, as the selection of run and measurement programs, the input of measurement parameters, such as choice of lens, illumination, optionally the focus setting, camera setting, etc, but also the input of how the measured values shall be stored, whether they are to be compared with each other and which evaluation method shall be selected. Information data can also be entered, such as the lot number of the wafers or their diameter or who the operating engineer is and the like. Since a recipe must be regarded virtually as a job, the recipe browser is also called the job browser, as is the case below and in the figures.
If there already exist data sets from previous measurements, they can be viewed in the data browser, after they have been retrieved correspondingly in the recipe browser.
To further facilitate storage or search of data sets, the directories and the subdirectories arranged in tree structures (as is known from the WINDOWS(copyright) operating system) can also be shown in another field on the screen. Preferably, the xe2x80x9cdirectory treexe2x80x9d is displayed in the left half of the screen. Thus, the user can retrieve directly the recipe and data sets, stored in a subdirectory; or he can store generated recipe and data sets in existing or newly generated subdirectories.
Thus, the entire browserxe2x80x94referred to as simply the browser in the followingxe2x80x94is divided into three areas:
(1) Left area: xe2x80x9cdirectoriesxe2x80x9d. Tree structure of the jobs stored in self-generating directories;
(2) Top right area: xe2x80x9cJobs of selected directoryxe2x80x9d shows the jobs of the selected directory; and
(3) Bottom right area: xe2x80x9cData of selected jobsxe2x80x9d or equivalent xe2x80x9cmeasurements of selected jobsxe2x80x9d shows the measurements of selected jobs.
The size of the areas can be scaled arbitrarily by the operator.
In the areas xe2x80x9cjobs of selected directoryxe2x80x9d and xe2x80x9cmeasurements of selected jobsxe2x80x9d the entries (lines) can be ordered according to specific criteria (columns). Columns of the job area are, for example: name, owner, scan type, layer stack, date of preparation, last change, etc. If one clicks a column heading, the content is ordered.
The advantages of the browser are, on the one hand, the easy selection of jobs by browsing in different content categories, according to which they can also be ordered. In the case of a few hundred jobs (measurement recipes), which are generated in a semiconductor plant, it is not only an obvious relief for both the operator and the engineer but also saves them time.
In addition, the selection of jobs is easier and it is possible to get a fast overview of the area xe2x80x9cmeasurements of selected jobsxe2x80x9d, displayed for each job. Here, the averages of all data measured with this job are listed, since the prehistory of the job can be inspected. It is possible to evaluate immediately without any detours the current measurement results, even with respect to previously measured data.
Following startup of the software, the job browser starts as the main screen. At the very top of the screen there is a toolbar. With the backspace key on the left of the toolbar, one always gets back to the main screen.
Besides the job browser, there are also as the main modules from the user""s point of view the job commander, which generates and edits the measurement and evaluation recipes (with xe2x80x9cbackxe2x80x9d being back to the browser) and the data commander for evaluating data details, generating graphics, etc.
The job commander serves to generate and edit measurement and evaluation recipes and is the main working tool for the engineer.
The main contents of a recipe are organized on tab cards (xe2x80x9cregister cardsxe2x80x9d). One of the tab cards, the page xe2x80x9capplicationxe2x80x9d, includes a xe2x80x9cresearchxe2x80x9d area. With the toolbar button xe2x80x9cmeasurexe2x80x9d a measurement can be performed, starting from any position of the job commander, at the current position with the current settings. The results and all of the important information (among other things, with the measurement spectrum) are displayed in the xe2x80x9cresearchxe2x80x9d area. Several such measurements can be stored in a research file and later reloaded. When browsing through the research measurements, the settings stored there are incorporated. The best setting can be incorporated into the current recipe.
The advantages of the job commander lie in the organization into tab pages and the interactive, storable and integratable research measurements from any position of the job commander. Thus, the engineer can easily find interactively the system settings that are best for the respective application. In addition, they can be stored and incorporated for subsequent repeat measurements or for the work of the operator on the production line.
Like the browser, the data commander is divided into several areas, which can also be freely scaled by the operator. In a top area xe2x80x9cmeasurements of job: namexe2x80x9d there is the same content as in the bottom area of the browser, namely the average values of the wafer measurements of the job. In the bottom area are the measurement points with respect to the wafer measurements, selected in the top area. On the right hand side of the screen are the operating elements that apply to the respective area.
The advantages of the data commander are the same xe2x80x9clook and feelxe2x80x9d as with the browser and the statistical data under each column.
Thus, the browser, the job commander and the data commander are designed for optimal user friendliness and easy and fast operation for complex optical inspection and measurement equipment, especially for the semiconductor industry. Besides the easy setup of measurement recipes and surveyable display of measurement results, the extreme flexibility of the modules also makes them suitable for fast adjustment to changing requirements.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.